This invention relates to integrated circuit current sources, and more particularly, to stable low-noise integrated circuit reference current circuits.
Alternating current (AC) and direct current (DC) current sources are used in a variety of integrated circuit applications. AC current sources have output currents that are controlled as a function of time. DC current sources have a fixed current and are therefore sometimes referred to as current references.
Stability and noise immunity are important characteristics for accurate DC current sources. Even though DC current sources operate at DC (O Hz), noise and the potential for unwanted signal oscillations are generally always present. If the circuit is unstable and prone to AC noise, DC performance will be adversely affected. DC current sources should also be relatively immune to changes in their system environment, so as not to place undesirable constraints on system designers.